Questions about System Notifications to Learners settings

I have a few questions about the system notifications settings for admins. 

1. Are default notifications sent even if they’re not set up in the learner notifications area for specific courses or course groups? Or are emails only sent when the individual notification is created and a specific trigger is set?
2. If a specific notification is disabled, does this mean individual emails set up in the learner notifications won’t be sent even though they’re set up to send based on triggers?
3. How are course notifications emails classified in the system email activity report category? “Campaign” seems to be the only outlier category in the list of possible categories, but how could we determine whether an email sent was a “course starts next week” or “Course starts tomorrow” email.